Showing papers on "Implementation published in 1978"

Using assertions about traces to write abstract specifications for software modules

Abstract: A specification for a software module is a statement of the requirements that the final programs must meet. In this paper we concentrate on that portion of the specification that describes the interface between the module being specified and other programs (or persons) that will interact with that module. Because of the complexity of software products, it is advantageous to be able to evaluate the design of this interface without reference to any possible implementations. The first sections of this paper present an approach to the writing of black box specifications, that takes advantage of Guttag's work on abstract specification [9]. Then we illustrate it on a number of small examples, and discuss checking the completeness of a specification. Finally we describe a case history of a module design. Although the module is a simple one, the early specifications (written using an earlier notation) contained design flaws that were not detected in spite of the involvement of several persons in a series of discussions about the module. These errors are easily recognized using the method introduced in this paper.

A graphics-based programming-support system

Abstract: A programming support system using extended Nassi-Shneiderman diagrams (NSD) is described. The aim of the work is to develop techniques for improving the quality and cost of specifying, documenting and producing computer programs. NSD's can be executed interpretively or compiled to produce running code. The system implementation has begun and charts can be drawn on a variety of display devices. The system is being developed using the Picture Building System developed earlier.

Synthesis of synchronization code for data abstractions

Abstract: Synchronization code is necessary to control shared access of an abstract data object in a parallel-processing environment. This thesis explores an approach in which a synchronization property can be specified in a high-level nonprocedural language and an implementation for the specified property can be synthesized algorithmically. A problem specification language is introduced in which synchronization properties can be expressed in a structured but natural manner. A method is then presented for synthesizing an implementation. An intermediate form, called a solution specification, is first derived, representing an abstract solution to the problem. The derivation of the solution specification accomplishes the transformation of the specification from nonprocedural to procedural from. The solution specification can be translated directly into a source language synchronization mechanism, such as a monitor. Specifications for common synchronization properties, such as the readers-writers and bounded buffer problems, are expressed in the problem specification language. Corresponding implementations are then synthesized for these problems. In addition, the derived solution specification can be used in analyzing the soundness of the original problem specification with respect to criteria such as freedom from deadlock and starvation.

Evaluating time/cost factors of implementation via GERT simulation

Abstract: Managers in striving for system implementation often disregard the time and cost that must be expended in achieving implementation success. This paper explores the use of GERT network analysis as a tool for planning and ascertaining the expected time and cost of implementation. The supporting base for the study is an implementation process that employs computer gaming for achieving organizational change.

Experience with a refinement paradigm in a knowledge-based automatic programming system

Abstract: PECOS is a knowledge-based system that constructs concrete implementations of abstract algorithms in the domain of symbolic programming. The rules in PECOS's knowledge base deal explicitly with many details of symbolic programming, including intermediate-level constructs and certain design decisions. Programs are synthesized by gradually refining the original specification into a program in the target language. By applying the refinement rules in its knowledge base, PECOS constructs a refinement tree: the root is the abstract specification, each leaf is an alternative implementation, and each path is a different sequence of rule applications. Thus, PECOS can construct a variety of different implementations for the same abstract specification.

Management information systems in health systems agencies: Some considerations

Abstract: Relevant considerations for the application of Management Information Systems theory (MIS) to public agencies are identified and discussed in this paper. The importance of the agency's environment, both external and internal, reporting structure and personnel makeup is examined. A specific application of these considerations in an MIS developed for the Health Systems Agency of Western New York is presented. Finally, the paper considers the importance of system implementation as well as system design.

Small systems for undergraduate courses in system design

Abstract: This paper discusses the problem of finding an appropriate target system for undergraduate system design classes. This system should allow the students to experience its life cycle, including full implementation through the programming and installations phases. The system case is chosen to be purposely small and immediately useful. The implementation language used is an extended BASIC, which greatly facilitates file manipulation and interactive programming. The system is designed to be menu-driven; that is, its activities are selected by the user from a menu display. Two specific implementations of such a system are described. One is in a small business, and the other is in a college classroom setting.